Centering device



Jan. 13, 1953 G. A. KWASNIEWSKI CENTERING DEVICE Filed June 5, 1951 INVENTOR GEORGE A. KWASNIEWSKI ATTORNEY Patented Jan. 13, 1953 UNITED STATES PATENT OFFICE CENTERING DEVICE George A. Kwasniewski, Mo'undview Township,

Ramsey County, Minn., assignor to Minneapolis flo'neywell Regulator Company, Minneapolis', Minn, a corporation of Delaware Application-June-S, 1951, SerialNo. 230,054

9 Claims.

This invention is directed to a centering device adapted to return two relatively pivoted members to a predetermined angular relationhip upon release of a force that has been applied to change that relationship.

One object of the invention is to provide a mechanical linkage that will return an angularly displaced member to a predetermined position when released from positions on either side of the predetermined position.

Another object is to provide such a centering device in which adjusting means is provided to serve the dual purpose of determining accurately the centered position and of eliminating any lost motion in the centered position.

A more specific object is to provide a manually operated potentiometer that is spring biased to a center position by a novel mechanical linkage.

Other objects will be evident from the following specification and claims and from the drawing in which Figure 1 shows the centering mechanism in centered position;

Figure '2 shows the same mechanism displaced from the centered position;

Figure 3 shows the device with the potentiometer mounted over the centering mechanism; and

Figure 4 is an elevation of the device as seen from the right of Figure 3.

The illustrated embodiment of the invention shows a manually operable potentiometer designed for use in connection with an airplane pilots control stick for modifying the course of an airplane as dictated by an autopilot. In actual practice two of the disclosed device's would be mounted at right angles to each other with one of them secured to a stationary member and the other rockable with the member that drives the first one, so that the control stick can control the airplane about both its pitch axis and its roll axis.

A supporting plate it is provided with holes u for mounting the device in an suitable manner. Three posts I2 hold an insulating plate is in spaced relation to the plate Til. A member including a shaft is extends through both plates ill and i5 and is journale'd therein "for pivotal movement about an axis normal to both plates. The shaft is pivotally positioned by a handle 28 secured to the back end thereof. The front an of the shaft It carries a contact arm 2? which, in turn, carries contacts 24 and 25 adapted to engage an electrical resistance winding 2e -a;o.d a contact bar (21. The resistance winding 25 to- 2 gether with the associated contact means co1lstitu'te a potentiometer that is actuated by movemerit of the handle as.

The shaft 18 has a 'disk Si] secured thereto t'erm-ediate the plates H! and I5 and this carries a pin 3! on an axis displaced from axis of the shaft l8, the disk and pin torn 1i h a crank movable with the shaft 48 and therefor with the potentiometer arm 22 and handle 23. A link 34 is pivotally connected to the pin 35 and extends to the right thereof as seen in Figures 1 and 2. The right hand end of link 3 has a slot 36 through which a pin 38 extends. The pin extends outwardly from an aim Gil which is pivoted at its upper end one pin ll mounted on the plate In and extends outwardly therefrom. The arm 40 is pivotally mounted so that the pin 33 is movable toward and away from the pivotal axis of the shaft [8. The lower extremity of the arm id is provided with a later-ally disposed abutment :3 adapted to engage a stop screw 14 that is adjustably carried in a self locking type nut it. The nut '45 is secured to a bracket it on the plate I0.

Another link dB is pivoted to the crank pin 3! and extends to the left. The left hand end of link 48 has a slot '49 through which a pin 5% er:- tends. The pin '5'! extends outwardly from an arm 52 which is pivoted at its upper end on a pin 53 which, in turn, is mounted in the plate 18 and extends outwardly therefrom. This arm is pivotally mounted so that the pin 5! is movable toward and away from the axis of the shaft is. The lower extremity of the arm 52 is p ovided with a laterally disposed abutment ss ted to engage a stop screw 56 that is ad os carried in a self-locking nut all. The nut i is secured to the left hand end of the hracl tet which carries the nut 15 on'its right hand end. A compression spring to acts between the lower extremities of the arms lit and 5-2 and biases each arm toward its associated stop screw.

Since the system with which the potentiometer is associated may require that the slider will return to a location on the resistance winding that is not exactly its physical center, and since manufacturing tolerances of the parts must be provided for, it is necessary to provide adjustment both for the location of the centered position and to assure a definite centered position. Thus, if the stop screws 44 and ar too close together the spring '60 will not be able to 3.1010. the arms 40 and '52 far enough apart so that the o ns 33 and 5! will engage the ends of the slot and 4B simultaneously, and the links 34 and 3 will not definitely locate the crank pin 3|. In this case release of the handle 20 will result in returning the contact arm 22 to a possible range of movement rather than to a definite point.

If the stop screws 44 and 56 are too far apart the spring 60 will hold the arms 40 and 52 against the ends of the slots 36 and 49 in the links 34 and 48, but a limited range of movement of the arms between the two stops would be permitted.

Proper adjustment is provided when the stop screws are adjusted so that both arms are in engagement with their respective stops and both pins 38 and 5| are in engagement with the outer ends of the slots 36 and 49 in the links 34 and 48, and when the contact 24 is in engagement with the desired center of the winding 26.

The inner ends of the slots 36 and 49 serve as stops to limit possible displacement of th handle 20 and contact arm 22 from the centered position. By way of illustration, in Figure 2 the handle 20 has reached its limit of possible clockwise movement since the inner end of the slot in link 48 is in engagement with pin 5| and the abutment 55 on th lower end of arm 52 is in engagement with stop screw 56.

Numerous modifications of the invention will be obvious. For instance, separate springs could be employed to bias the two arms. Also the parts could be reversed so that the shaft 18 would be relatively stationary and the plates and I turned to obtain the desired control function.

Likewise, it is obvious that the links 34 and 48 could be reversed so that the slots are at the crank pin 3|, or the length of the slots could be distributed between the two ends of the links.

I claim as my invention:

l. Centering means for an oscillatable member comprising, a support, a member pivoted in said support, first and second arms pivotally mounted on said support for movement toward and away from the pivotal axis of said member and each of said arms having a pin extending outwardly therefrom, a crank pin on said member, first and second links pivoted on said crank pin and engaging the pins on said first and second arms respectively by means of elongated slots therein, spring means acting on said arms to bias said arms toward a position in which the pins on said arms engage the outer ends of the slots in said links, and stops on said support adapted to engage said arms to limit outward movement thereof.

2. Centering means for an oscillatable member comprising, a support, a member pivoted in said support, first and second arms pivotally mounted on said support for movement toward and away from the pivotal axis of said member and each of said arms having a pin extending outwardly therefrom, a crank pin on said member, first and second links pivoted on said crank pin and engaging the pins on said first and second arms respectively by means of elongated slots therein, spring means acting on said arms to bias said arms toward a position in which the pins on said arms engage the outer ends of the slots in said links, and stops on said support adapted to engage said arms to limit outward movement thereof, said stops being so located that when both arms are in engagement with said stops the pins on said arms are in ngagement with the outer ends of the slots in each of said links.

3. Centering means for an oscillatable member comprising, a support, a member pivoted in said support, first and second arms pivotally mountedon said support for movement toward an a y from the pivotal axis of said member and each of said arms having a pin extending outwardly therefrom, a crank pin on said member, first and second links pivoted on said crank pin and engaging the pins on said first and second arms respectively by means of elongated slots therein, spring means acting on said arms to bias said arms toward a position in which the pins on said arms engage the outer ends of the slots in said links, and stops on said support adapted to engage said arms to limit outward movement thereof, said stops being so located that when both arms are in engagement with said stops the pins on said arms are in engagement with the outer ends of the slots in each of said links, the inner ends of the slots in each of said links determining the maximum possible displacement of said member away from centered position.

4. Centering means for an oscillatable member comprising, a support, a shaft pivoted in said support, first and second arms pivotally mounted on said support on opposite sides of said shaft and adapted to swing toward and away from said shaft, stops on said support limiting movement of each of said arms in a direction away from said shaft, spring means biasing each of said arms toward its associated stop, a crank on said shaft, and first and second links interconnecting said first and second arms respectively and said crank, each of said links fixing the maximum distance between its associated arm and said crank but permitting a reduction in such distance when said crank is moved by rotation of said shaft to pull the opposite arm away from its associated stop.

5. Centering means for an oscillatable member comprising a support, a shaft pivoted in said support, first and second arms pivotally mounted on said support on opposite sides of said shaft and adapted to swing toward and away from said shaft, stops on said support limiting movement of each of said arms in a direction away from said shaft, spring means biasing each of said arms toward its associated stop, a crank on said shaft, and first and second links interconnecting said first and second arms respectively and said crank, each of said links fixing the maximum distance between its associated arm and said crank but permitting a reduction in such distance when said crank is moved by rotation of said shaft to pull the opposite arm away from its associated stop, and means for independently varying the position of each of said stops.

6. Centering means for a control device comprising, a support, a member pivoted in said support, control means actuated by relative movement between said support and said member, said control means having a null intermediate position, first and second arms pivotally mounted in said support for movement toward and away from the pivotal axis of said member, spring means biasing each of said arms, outwardly from the pivotal axis of said member, stops on said support adapted to engage said arms to limit movement thereof outwardly from the pivotal axis of said member, a crank on said member, means interconnecting said crank and said first and second arms for moving said arms selectively away from said stops, and means for adjusting the position of said stops with respect to said support so that both of said arms are in engagement with said stops when said control means is in.its null position.

support, control means actuated by relative movement between said support and said member, said control means having a null intermediate position, first and second arms pivotally mounted in said support for movement toward and away from the pivotal axis of said member, spring means biasing each of said arms, outwardly from the pivotal axis of said member, stops on said support adapted to engage said arms to limit movement thereof outwardly from the pivotal axis of said member, a crank on said member, first and second links interconnecting said crank and said first and second arms respectively, each of said links having one effective length when in tension and a lesser effective length when in compression, and means for adjusting the position of said stops with respect to said support so that both of said arms are in engagement with said stops with both links at their maximum effective length and with said control means in its null position, the minimum efiective length of each of said links being effective in cooperation with the associated arm and stop to limit the possible angular deflection of said member from the centered position.

8. Centering means for an oscillatable member comprising, a support, a member pivoted in said support, first and second arms pivotally mounted on said support for movement toward and away from the pivotal axis of said member and each of said arms having a pin extending outwardly therefrom, a crank pin on said member, first and second links interconnecting said crank pin and said pins on said first and second arms respectively, each of said links having different maximum and minimum effective lengths, spring means biasing one of said arms in a clockwise direction and the other of said arms in a counterclockwise direction, and stops on said support adapted to engage each of said arms to limit movement thereof in the direction in which it is biased by said spring means.

9. Centering means for an oscillatable member comprising, a support, a shaft pivoted in said support, first and second arms pivotally mounted on said support on opposite sides of said shaft and adapted to swing toward and away from said shaft, stops on said support limiting move ment of one of said arms in a clockwise direction and limiting movement of the other of said arms in a counterclockwise direction, spring means biasing each of said arms toward its as sociated stop, a crank on said shaft, and first and second links interconnecting said first and second arms respectively and said crank, each of said links fixing the distance between its associated arm and said crank for movement of said arm away from its stop due to movement of said crank but permitting movement of said crank in the opposite direction to move the other arm away from its associated stop.

GEORGE A. KWASNIEWSKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,389,692 Pennington et a1. Sept. 6, 1921 FOREIGN PATENTS Number Country Date 687,518 Germany Jan. 31, 1940 

